I have seen only now your message. We have the same difficulty in recieving the DTV tv signal also mooring in places where the tv signal is very good.
I Confirm the possible shortcut on the head of the mast and the huge signal dispersion In fact I noticed that one we switch on the main mast navigation lights and the while the tv is on we have the termic switch of the lights that swich off.
Do you have a picture of the masterhead you mentioned .?
I have understood from your email that this cover contains the connection with the antenna and the rusted part is inside and not visible from a simple visual inspection on the mast head. Am I right ?
Desiree SM 304